/*
 * Copyright (c) 2007-2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: XNull.java,v 1.2.4.1 2005/09/14 20:34:46 jeffsuttor Exp $
 */
package com.sun.org.apache.xpath.internal.objects;

import com.sun.org.apache.xml.internal.dtm.DTM;
import com.sun.org.apache.xpath.internal.XPathContext;

/**
 * This class represents an XPath null object, and is capable of
 * converting the null to other types, such as a string.
 * @xsl.usage general
 */
public class XNull extends XNodeSet {
    static final long serialVersionUID = -6841683711458983005L;

    /**
     * Create an XObject.
     */
    public XNull() {
        super();
    }

    /**
     * Tell what kind of class this is.
     *
     * @return type CLASS_NULL
     */
    public int getType() {
        return CLASS_NULL;
    }

    /**
     * Given a request type, return the equivalent string.
     * For diagnostic purposes.
     *
     * @return type string "#CLASS_NULL"
     */
    public String getTypeString() {
        return "#CLASS_NULL";
    }

    /**
     * Cast result object to a number.
     *
     * @return 0.0
     */

    public double num() {
        return 0.0;
    }

    /**
     * Cast result object to a boolean.
     *
     * @return false
     */
    public boolean bool() {
        return false;
    }

    /**
     * Cast result object to a string.
     *
     * @return empty string ""
     */
    public String str() {
        return "";
    }

    /**
     * Cast result object to a result tree fragment.
     *
     * @param support XPath context to use for the conversion
     *
     * @return The object as a result tree fragment.
     */
    public int rtf(XPathContext support) {
        // DTM frag = support.createDocumentFragment();
        // %REVIEW%
        return DTM.NULL;
    }

    //  /**
    //   * Cast result object to a nodelist.
    //   *
    //   * @return null
    //   */
    //  public DTMIterator iter()
    //  {
    //    return null;
    //  }

    /**
     * Tell if two objects are functionally equal.
     *
     * @param obj2 Object to compare this to
     *
     * @return True if the given object is of type CLASS_NULL
     */
    public boolean equals(XObject obj2) {
        return obj2.getType() == CLASS_NULL;
    }
}
